/**
 * Copyright (c) 2012-2016, www.tinygroup.org (luo_guo@icloud.com).
 * <p>
 * Licensed under the GPL, Version 3.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.gnu.org/licenses/gpl.html
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.tinygroup.commons.match;

import org.tinygroup.commons.tools.StringEscapeUtil;

import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Package-protected helper class for {@link AntPathMatcher}. Tests whether or not a string matches against a pattern
 * using a regular expression.
 *
 * <p>The pattern may contain special characters: '*' means zero or more characters; '?' means one and only one
 * character; '{' and '}' indicate a URI template pattern.
 *
 * @author Arjen Poutsma
 * @since 3.0
 */
public class AntPathStringMatcher {

    private static final Pattern GLOB_PATTERN = Pattern.compile("\\?|\\*|\\{([^/]+?)\\}");

    private static final String DEFAULT_VARIABLE_PATTERN = "([^/]*?)";

    private final Pattern pattern;
    private final List<String> variableNames = new LinkedList<String>();
    private final Map<String, String> uriTemplateVariables = new HashMap<String, String>();
    private String str;

    /** Construct a new instance of the <code>AntPatchStringMatcher</code>. */
    public AntPathStringMatcher(String pattern, String str) {
        this.str = str;
        this.pattern = createPattern(pattern);
    }

    private Pattern createPattern(String pattern) {
        StringBuilder patternBuilder = new StringBuilder();
        Matcher m = GLOB_PATTERN.matcher(pattern);
        int end = 0;
        while (m.find()) {
            patternBuilder.append(quote(pattern, end, m.start()));
            String match = m.group();
            if ("?".equals(match)) {
                patternBuilder.append('.');
            } else if ("*".equals(match)) {
                patternBuilder.append(".*");
            } else if (match.startsWith("{") && match.endsWith("}")) {
                int colonIdx = match.indexOf(':');
                if (colonIdx == -1) {
                    patternBuilder.append(DEFAULT_VARIABLE_PATTERN);
                    variableNames.add(m.group(1));
                } else {
                    String variablePattern = match.substring(colonIdx + 1, match.length() - 1);
                    patternBuilder.append('(');
                    patternBuilder.append(variablePattern);
                    patternBuilder.append(')');
                    String variableName = match.substring(1, colonIdx);
                    variableNames.add(variableName);
                }
            }
            end = m.end();
        }
        patternBuilder.append(quote(pattern, end, pattern.length()));
        return Pattern.compile(patternBuilder.toString());
    }

    private String quote(String s, int start, int end) {
        if (start == end) {
            return "";
        }
        return Pattern.quote(s.substring(start, end));
    }

    /**
     * Main entry point.
     *
     * @return <code>true</code> if the string matches against the pattern, or <code>false</code> otherwise.
     */
    public boolean matches() {
        Matcher matcher = pattern.matcher(str);
        if (matcher.matches()) {
            if (uriTemplateVariables != null) {
                for (int i = 1; i <= matcher.groupCount(); i++) {
                    String name = this.variableNames.get(i - 1);
                    String value = StringEscapeUtil.unescapeURL(matcher.group(i));
                    uriTemplateVariables.put(name, value);
                }
            }
            return true;
        } else {
            return false;
        }
    }

    public List<String> getVariableNames() {
        return variableNames;
    }

    public Map<String, String> getUriTemplateVariables() {
        return uriTemplateVariables;
    }
}
